1. Field of the Invention
This invention relates to silicone elastomer compositions which cure on substrates to self-adhering elastomers and to methods of preparation.
2. Description of the Prior Art
Adhesion of silicone elastomers to substrates has been a problem which has taken many forms. Priming a substrate prior to applying an uncured silicone elastomer composition is one solution. The priming methods are adequate for the purpose of achieving a strong bond, but they suffer from the inconvenience of being at least two step processes. Another approach to the adhesion problem is the use of one or more additives in compositions to impart the adhesion property between a cured elastomer and a substrate. Additives are usually specific for each composition, application and condition under which they are used. Most additives have shortcomings, such as interfere with cure or vulcanization of the composition, cause one or more of the cured properties of the product to decrease, are limited to the substrates to which the cured composition will bond, reduce the shelf stability of the composition and increase the cost of the composition significantly.
The present invention is of the additive type in which the additive is a combination of an epoxy silane and a hydroxylated polysiloxane containing vinyl. It is known in the art to add epoxide compounds including silicon-containing epoxide compounds to silicone rubber to improve its tear strength, as described by Nitzsche et al. in U.S. Pat. No. 3,131,161. It is also known that certain organosilicon compounds which contain, in the same molecule, an alkenyl group and a group of the formula EQU Q(XO).sub.2 Si--
where Q is an epoxy-containing monovalent hydrocarbon radical and X is a lower alkyl group, can be added to silicone compositions which cure through the reaction of alkenyl groups and silicon-bonded hydrogen atoms to improve the adhesion of the cured composition to substrates.